1 EE40 Summer 2010 Hug EE40 Lecture 7 Josh Hug 7/7/2010

2 EE40 Summer 2010 Hug Blackboard Stuff HW3 concerns Any general questions people might have

3 EE40 Summer 2010 Hug General Info No lab today Midterm on Friday in class –12:10-1:30 [be on time!] –No electronic devices –One 8.5”x11” (or A4) sheet of paper Handwritten anything you want, both sides HW4 due next Friday (will be posted Friday) No positive feedback circuits on the midterm (but there might be on the final)

4 EE40 Summer 2010 Hug Project 2 Project 2 spec to be posted over the weekend If you’d like to do something other than the official project, you can submit a specification for your Project 2: –Team members (up to 3) –Parts list –Schematic Must have substantial hardware component –Microcontrollers are OK, but your project shouldn’t be about assembly programming –MyDAQ is also OK, but your project shouldn’t be about LabVIEW programming Custom project proposals due WEDNESDAY by 5 PM

5 EE40 Summer 2010 Hug Guest Mini-Lecture Today Jeff Jansen from National Instruments will be talking today for the last half hour –MyDAQ data acquisition device USB device that lets you use your computer in lieu of big bulky specialized test equipment –Can use this device to do labs from home or anywhere else a laptop functions –If anyone wants to use these in labs, we will have 10 of them available –Could be handy for Project 2 Must have substantial hardware component (can’t just be LabVIEW software written for MyDAQ)

6 EE40 Summer 2010 Hug Course Website I am assured that the rest of the calendar and the other 5 labs will be posted shortly. Most likely schedule is: –7/13: Project 1 (buzzer) –7/14: Sound synthesizer –7/20: Power supply –7/21: Active filter lab –7/27-8/11: Project 2 Future reading assignments will be posted 3 days before they’re due –Micro-deadlines are needed for me, too!

7 EE40 Summer 2010 Hug Op-Amp Saturation Remember those power ports we’ve been ignoring?

8 EE40 Summer 2010 Hug Op-Amp Saturation Example V in VoVo -5 V-12V -1V-3V 2V6V 1,512,312V12V -12V 4V -4V

9 EE40 Summer 2010 Hug Positive Feedback On the board

10 EE40 Summer 2010 Hug Another Op-Amp Model Revision

11 EE40 Summer 2010 Hug Common Mode Signal _+_ V1V1 -10V 10V 0V New Term

12 EE40 Summer 2010 Hug Common Mode Signal _+_ V1V1 -10V 10V

13 EE40 Summer 2010 Hug Example of using CMRR

14 EE40 Summer 2010 Hug One of many Op-Amp parameters Typical CMRR is 35,000 (~90 dB) –Usually measured in db CMRR db =20*log 10 (CMRR) In real life, Op-Amps come with multipage data sheets (as do everything else)

15 EE40 Summer 2010 Hug How are you feeling about… How are you feeling about Node Voltage and solving basic circuits? –A. Completely lost –B. A little behind –C. Alright –D. Pretty good –E. Feel like I’ve attained mastery

16 EE40 Summer 2010 Hug How are you feeling about… How are you feeling about I-V characteristics and Thevenin and Norton equivalents? –A. Completely lost –B. A little behind –C. Alright –D. Pretty good –E. Feel like I’ve attained mastery

17 EE40 Summer 2010 Hug How are you feeling about… How are you feeling about Op-Amp circuits? –A. Completely lost –B. A little behind –C. Alright –D. Pretty good –E. Feel like I’ve attained mastery

18 EE40 Summer 2010 Hug How are you feeling about… How are you feeling about the midterm? –A. Terrified –B. A little scared –C. Neutralish –D. Feel prepared –E. Feel like I will do excellently

19 EE40 Summer 2010 Hug Make up Labs Do you need a make up lab? A. Yes B. No

20 EE40 Summer 2010 Hug This is where we stopped

21 EE40 Summer 2010 Hug UNIT 2 Elements with Memory a.k.a. Energy Storage Elements

22 EE40 Summer 2010 Hug Preview of Unit 2

23 EE40 Summer 2010 Hug RC Circuits Taking the Live Demo risk, let’s check out a quick qualitative circuit simulation

24 EE40 Summer 2010 Hug The Capacitor The basic idea is pretty simple –Imagine you have two parallel metal plates, both of which have equal and opposite excess charges –Plates are separated by an insulating layer (air, glass, wood, etc) The charges would love to balance out Insulator blocks them (just as the ground blocks you from falling into the center of the earth)

25 EE40 Summer 2010 Hug The Capacitor

26 EE40 Summer 2010 Hug The Capacitor Remember that a voltage is the electrical potential between two points in space

27 EE40 Summer 2010 Hug The Capacitor

28 EE40 Summer 2010 Hug The Capacitor Lots of current Zero V C Zero current V C =V S Lots of current High V C Zero of current Zero V C

29 EE40 Summer 2010 Hug Symbol: Units: Farads (Coulombs/Volt) Current-Voltage relationship: or Note: v c must be a continuous function of time since the charge stored on each plate cannot change suddenly Capacitor +vc–+vc– icic C C (typical range of values: 1 pF to 1  F; for “supercapa- citors” up to a few F!) Electrolytic (polarized) capacitor C These have high capacitance and cannot support voltage drops of the wrong polarity

30 EE40 Summer 2010 Hug Node Voltage with Capacitors On board +vc–+vc– icic

31 EE40 Summer 2010 Hug Ordinary Differential Equations Inductors, too, give us a simple 1 st order relationship between voltage and current Node Voltage with memoryless circuits gave us algebraic equations Node voltage with elements with memory will give us Ordinary Differential Equations (ODEs) Next week will be a bunch of setting up and solving 1 st and 2 nd order linear ODEs Higher order and especially nonlinear ODEs are tough to solve. For example…

32 EE40 Summer 2010 Hug Chua’s Circuit –ODEs are:

33 EE40 Summer 2010 Hug Chua’s Circuit Despite simplicity of ODEs Exhibits chaos! Invented by current UC Berkeley EECS professor Leon Chua in 1983

34 EE40 Summer 2010 Hug Capacitors Useful for –Storing Energy –Filtering –Modeling unwanted capacitive effects, particularly delay

35 EE40 Summer 2010 Hug Good luck on your midterm! Now on to Jeff’s presentation